This invention relates to alkaline batteries. More particularly, the invention relates to separators for alkaline batteries. Still more particularly, the invention relates to such separators which comprise cross-linked polyvinyl alcohol copolymers.
Alkaline batteries are well known and are described in considerable detail in the literature, including U.S. Pat. No. 2,635,127 of Yardney et al; U.S. Pat. No. 2,648,717 of Ross et al; U.S. Pat. No. 4,269,869 of Mendelsohn; and U.S. Pat. No. 4,157,423 of Gaddesaud, the disclosure of each of which is incorporated herein by reference.
One of the key items of an alkaline battery is the separator, a membrane which is interposed between the electrodes of the battery and which is in contact with the alkaline electrolyte. Battery separators are discussed at some length in the foregoing patents and elsewhere, including the following patents: U.S. Pat. No. 4,085,241 of Sheibley; U.S. Pat. No. 4,154,912 of Philipp et al.; and U.S. Pat. No. 4,224,393 of Fienberg et al., the disclosure of each of which is incorporated herein by reference.
One type of battery separator which has received considerable attention, and which is referred to in several of the foregoing patents, comprises cross-linked polyvinyl alcohol. These separators are typically made by casting an aqueous solution containing 5-20% by weight of film-forming polyvinyl alcohol into a film, and drying and cross-linking the film. Cross-linking may be achieved in any of several ways, such as by treatment of the polyvinyl alcohol film with an acid solution of an aldehyde cross-linking agent. Suitable methods include those disclosed in U.S. Pat. No. 4,157,423 of Gaddesaud; U.S. application Ser. No. 145,271, now U.S. Pat. No. 4,272,470 of Hsu et al; and U.S. Pat. No. 4,262,067 of Philipp et al., the disclosure of each of which is incorporated herein by reference.
While the cross-linked polyvinyl alcohol battery separators known heretofore have proven to be satisfactory, there is a continuing need for improvement, particularly in battery performance. It is an object of the present invention to provide a battery having a battery separator which enhances alkaline battery performance and to provide alkaline batteries with enhanced performance.